Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 10, 1997
Publication Date: N/A
Interpretive Summary: Although Se is an essential micronutrient, high concentrations of Se can be toxic to animals and humans. Plants that accumulate high concentrations of Se have been proposed to remediate Se-laden soils. Such plants can be harvested and used as feed supplements in Se-deficient areas. We evaluated the release of Se from plant residues containing high Se concentrations and from cattle manure derived from these plants. Selenized plant residue and animal manure can be used as slow release fertilizers in Se-deficient soils. Adding organic materials to soils containing high soluble Se reduces Se availability to plants. These results provide basic information on Se transformation in soils to help determine strategies for lowering Se concentrations in Se-laden soils and to supplement animal diets in Se-deficient soils.
Technical Abstract: The uptake of inorganic selenate and organic selenium (Se) by successive plantings of canola (Brassica napus) and multiple clippings of tall fescue (Festuca arundinacea L.) was studied under growth chamber conditions. Selenium was added to two diverse soils at a rate of 1.5 mg Se/kg soil as inorganic selenate solution or as seleniferous organic materials [alfalfa (Medicago sativa), Astragalus praelongus, or cattle manure]. Tissues of canola and tall fescue accumulated greater concentrations of Se from the selenate treatment compared to the treatments with seleniferous organic materials. In the selenate-treatment, average leaf Se concentrations varied between soils and ranged from 218 to 284 mg Se/kg DM for canola, and from 52 to 75 mg Se/kg DM for tall fescue. The addition of non-seleniferous crop residue or animal manure to the selenate-treated soils considerably reduced Se accumulation by both plant species. In soils treated with seleniferous organic materials, leaf Se concentrations of canola or tall fescue were less than 10 mg Se/kg DM. A selenium mass balance for the various treatments was computed.